Generally, a plurality of chasses are installed into a cabinet through slide rail structures such that the slide rail structures are arranged between the chasses and the cabinet for pushing and pulling the chasses to easily access the cabinet. However, after the chasses are placed in the cabinet, it will become extremely heavy. Although it is easy to push and fully pull these severs in and out, the position of the center of gravity of the cabinet will change after several chasses are pulled out at the same time.